Closure apparatus for pressure chamber



p 1964 R. D. CASTLE ETAL 3,147,068

CLOSURE APPARATUS FOR PRESSURE CHAMBER Filed March 1, 1962 2 Sheets-Sheet 1 g! ATTORNEYS United States Patent 3,147,068 CLOSURE APPARATUS FOR PRESSURE CHAMBER Richard D. Castle and Sam Papaiia, Rochester, N.Y.,

assignors to Wilmot Qastle Company, Rochester, N.Y.,

a corporation of New York Filed Mar. 1, 1962, Ser. No. 176,728 Claims. (Cl. 2198) This invention relates to closure apparatus for a pressurized chamber and particularly for use with a steam sterilization chamber.

The basic concept of this invention comprises a sliding tray extending through an opening in the sterilizer chamber, and having rigidly mounted at opposite ends thereof two plates, a closure plate and a locking plate. The closure plate is adapted for closing and sealing the opening through which the tray otherwise extends. The locking plate is slidably sealed to the inside periphery of the sterilizer chamber so that an outside surface of the locking plate is sealed from the pressure inside the sterilizer while an inside surface of the locking plate is exposed to that pressure. When the closure plate is substantially closed, the inside surfaces of both plates facing each other are both exposed to the internal pressure of the sterilizer.

The basic principle of this invention resides in producing a greater force or total pressure on the locking plate, carried internally of the sterilizing chamber, in a direction away from an open position than the total pressure applied to the closure plate in the opposite direction. This principle of differential total pressures may be accomplished by a reduction of pressure on the outside surface of the locking plate, sealed against internal pressure of the chamber, to a value sufficiently less than atmospheric pressure present on the outside surface of the closure plate to maintain the tray and attached plates in the closed position. Also, the simplest and most novel manner of providing the differential total pressure is by making the inside surface of the locking plate, exposed to the internal pressure of the chamber, of sufficiently larger area than the inside surface of the closure plate to maintain the tray and attached plates in the closed position.

In the sterilizer art, it has heretofore been necessary to provide doors or closure plates having various locking devices for maintaining the door in the closed position when the chamber is pressurized, whereas this invention provides the novelty of the second plate, rigidly attached to the door by means of the tray, being supported internally of the chamber and having only one surface responsive to internal pressure of the chamber.

The novel concept of making the inside surface area of the locking plate, carried inside of the chamber, larger than the inside surface of the door is particularly novel and useful for sterilization, in that this construction de pends completely upon the internal pressure of the chamber. The operator is prevented from opening the door to the sterilizer or other pressurized chamber until the internal pressure of the chamber itself has been reduced to a safe value.

Therefore, it is a significant object of this invention to provide closure apparatus for a sterilizer or other pressurized chamber which obviates the necessity of latch elements commonly thought of as necessary for pressurized chambers.

A further object of our invention is the provision of closure locking apparatus for a sterilizer or other pressurized chamber based on sufiicient differential total pressure, applied to a locking plate carried internally of the chamber and a closure plate or door, to maintain the latter in a closed position.

'ice

Another object of this invention is to provide closure apparatus for a sterilizer or other pressurized chamber having a locking plate rigidly spaced from a closure plate and having a larger surface area exposed to internal pressure of the chamber than the closure plate.

It is a further object of this invention to provide simpier, more satisfactory, and less expensively manufactured closure apparatus for sterilizers and other pressurizable chambers.

An additional feature of this invention is the selective increase and decrease of pressure on the outside surface of the locking plate sealed from internal pressure of the chamber for selectively controlling the opening and closing of the door respectively. Hence, it is another object of this invention provide apparatus for selectively controlling the opening and closing of a door or closure member for a sterilizer or other pressurizable chamber by pressure.

Other objects and advantages of this invention will particularly be set forth in the claims and will be apparent from the following description, when taken in connection with the accompanying drawings, in which:

FIG. 1 is a side elevational view in section of one embodiment of this invention.

FIG. 2 is a side elevational view in section of a second embodiment of this invention.

FIG. 3 is a side elevational view in section of a third embodiment of this invention.

With reference to FIG. 1, a vessel generally indicated by the numeral 10 defines a pressurizable chamber comprising a cylindrical shell or main body portion 12, opposite ends of which are rigidly mounted in annular grooves 14 and 16 of a vertically disposed back plate 18 and a vertically disposed front plate 20, respectively.

Front plate 20 has a circular opening 22, including an outwardly tapered portion 24. Opening 22 slidably supports a substantially cylindrically shaped tray or basket 26. A door or closure member 28 and a locking plate 30 are rigidly mounted at opposite ends of tray 25, which serves to connect plates 28 and 30 in spaced relationship.

It will be understood that in the preferred embodiment of the invention illustrated in FIG. 1, that the locking plate 30 is larger in diameter than the closure plate 28.

Plate 28 is provided with an annular peripheral groove 32 receiving an O-ring seal 3 adapted for sealing the closure plate 28 within annular opening 22;. The locking plate St]? is likewise provided with a peripheral groove 3.6 receiving an annular O-ring seal 38 for slidably sealing plate 30 to the inside periphery 49 of the cylindrical shell 12.

Closure plate 28 is provided with a handle 42, rigidly mounted thereon by a bolt 44, for manual control of the tray 26. Tray 26 is preferably adapted to receive medical or dental instruments for sterilization within the sterilizing vessel lti.

Shell 12 is provided with an inlet fitting 46 and an outlet fitting 48. An inlet hole or bore 56) of fitting 46 is larger in diameter than a corresponding outlet hole or opening 52 of fitting 48 for the purpose hereinafter described. Steam is introduced through a valve 54 from a source of steam under pressure. Steam is diagrammatically indicated by the arrow 56 entering fitting 46 and being discharged through fitting 48 as indicated by the arrow 58.

A plurality of perforations 60 are provided in the tray 26 for diffusion of the steam after passing through the articles (not shown) to be sterilized therein, thereby facilitating the discharge of steam out the bottom of tray 26 through outlet opening 52. and preventing any substantial accumulation of condensation in the bottom of the tray.

It will be understood that as the tray 26 and attached plates 28 and 30 are moved from an open position, such as illustrated in FIG. 1, to a closed position, as illustrated in FIG. 3, in which the closure plate 28 and opening 22 are in vertical or radial alignment, the seal 38 slidably seals an outside surface 62 of locking plate 36 from the internal steam pressure of the shell 12. When the closure plate 28 is in the closed position with the opening 22, the right hand portion of the shell 12 surrounding locking plate 30 must be concentric therewith in order to maintain sealed relationship between locking plate 30 and shell 12. A portion of shell 12 generally indicated by the numeral 64 is of varying volumetric area depending upon the position of locking plate 30 relative to back plate 18. Portion 64 of the sterilizer shell 12 communicates through a conduit 68 with either atmosphere or a pressure reducing system 69. Portion 64 must be vented in order for the air therein to escape as the tray 26 is moved from the open position to the closed position and for air to return to portion 64 upon opening of the tray 26.

From the above description, it will be understood that after the tray 26 has been filled with the dental, medical or other instruments or articles to be sterilized therein and moved to the closed position above described, the steam will be introduced into the shell 12 through valve 54 and inlet opening 50.

It is significant that the inlet 46 is provided intermediate plates 28 and 30 when in the closed position. The force or total pressure on the outside or external surface 62 of locking plate 30 is, at least, no greater than the force or total pressure on an outside or external surface 70 of the closure plate 28 in the opposite direction. The total steam pressure exerted on the inside surface 66 of the larger diameter locking plate 30 is sufficient to overcome the total pressure exerted on an inside surface 72 of the smaller diameter closure plate 28 and exert a force on the locking plate 30 in a direction to the right as viewed in FIG. 1, thereby to maintain tray 26 and attached plates 28 and 30 in the closed and sealed position.

Increased and decreased pressure from a pressure control system 69 controls the movement of the tray 26 between the open and closed positions respectively. In this regard, the locking plate 30 serves as a piston.

After the instruments have been received in the tray 26, a manually operated treadle (not shown), controlling the pressure system 69, is actuated to effect a withdrawal of air from portion 64 in the direction indicated by an arrow 74, thereby to move the sealed locking plate 30 to the right until the closed position is reached. Thereafter, the vacuum produced by the pressure system 69 may be maintained to increase the total pressure on the locking plate 30 in a direction to the right as viewed in FIG. 1 or it may be discontinued.

After sterilization has been completed in the vessel 10, the flow of air from the pressure system 69 may be reversed to introduce increased air pressure, indicated by the arrow 76, thereby to move the tray 26 to the left, as viewed in FIG. 1, to the open position again.

The differential size of the inlet and outlet openings 50 and 52 permits the steam being introduced through inlet opening 50 to flow into the vessel at a faster rate than it is expelled through the smaller diameter opening 52. Thus, steam pressure builds up inside the vessel despite continued exhaust. The illustrated embodiment of FIG. 1 shows a diameter ratio of 3:1. It will be understood that this ratio could be varied to meet specified conditions. Bacteriacidal action is effected by building up the steam pressure to a peak well above the necessary sterilizing pressure, as for example, to a peak of 60 pounds per square inch (p.s.i.) and thereafter cutting off the steam pressure. In order to build up a chamber pressure of, for example, 60 p.s.i., a line pressure of at least 70 p.s.i. is preferable for a construction where the inlet opening is inch diameter and the outlet opening is inch diameter; such a construction contemplates a sterilizing cycle lasting between 40 and 60 seconds. The relative size of the inlet and outlet openings depend on the line pressure of the steam and the size of the vessel. Each of these factors can be varied to give the desired cycle starting at zero pressure and preferably going to 60 p.s.i. chamber pressure and dropping back down to zero pressure.

In order to automatically accomplish the above de scribed cycle, a pressure or temperature responsive device such as a pressure sensitive bellows 78 is provided in open communication with the inside of vessel 10 through a conduit 80. Bellows 78 carries a contact switch 82 which makes and breaks a circuit, including a contact 84, which closes valve 54 when the chamber pressure reaches a selected value such as 60 p.s.i. After the valve 54 is closed, the chamber pressure drops from the selected peak value of 60 p.s.i. to atmospheric pressure. Thus, apparatus is provided whereby the sterilizing chamber defined by the shell 12 is always open to atmospheric pressure with an outlet of selected size sufficiently small enough to permit pressurization of the sterilizing chamber up to a selected peak value, at which value the valve 54 is automatically closed to cut off steam pressure to the chamber, and the chamber pressure then drops down to atmospheric pressure.

Thus, a complete cycle has been described and after the internal pressure of the vessel 10 has reached atmospheric pressure the operator may manually open the tray 26 by pulling handle 42 to the left as viewed in FIG. 1 if the sealed portion 64 of the shell 12 is vented to atmosphere, or in the alternative, depress the treadle (not shown) for operating the fluid pressure system 69 to introduce air pressure indicated by the arrow 76 into the sealed portion 64 and automatically move the tray 26 to the left.

Illustrated at FIG. 2 is an embodiment of this invention in which all of the parts included within the brokenline rectangle 85, having suffixes A, correspond to the same numbered element of FIG. 1 without the sufiix A. In FIG. 2, the parts encircled by broken line 85 are adapted for closing and sealing a larger pressurizable chamber generally indicated by the numeral 86.

The pressurized chamber 86 might well be a fuel tank on an airplane or any other pressurized chamber. In the event that this invention is used for closing and sealing an aircraft fuel tank, it will be understood that fuel is introduced through the opening 22A. In this particular embodiment, the sealed portion 64A of vessel 10A is vented to atmosphere through a conduit 68A which rigidly supports the back end or back plate 18A of the vessel 10A. It will be further understood that the pressure built up in the larger vessel 86 will communicate with the inside surfaces 66A and 72A of plates 28 and 30 through both fittings 46A and 48A.

With reference to FIG. 3, this embodiment of this invention has parts corresponding to those illustrated in FIG. 1 which are designated by the same numeral followed by the sufiix B. In this embodiment, the closure plate 28B and the locking plate 30B are of the same diameter. Differential forces or total pressures on plates 28B and 30B, to effect locking of the composite tray 26B, plate 28B and plate 30B in a closed and sealed position, is fulfilled by continuously applying reduced pressure to the outside surface 62B of plate 30B, as indicated by the arrows 90. This reduction in air pressure is created by pressure system 693. Internal pressure of the vessel between plates 28B and 30B exerted on the inside surfaces 72B and 66B thereof, respectively illustrated by the arrows 92 and 91, are equal and counterbalance each other. Arrows 93 illustrate atmospheric pressure exerted on the outside surface 70B of plate 28B.

Thus, the internal pressure in the chamber exerted over equal surface areas, as indicated by arrows 91 and 92, simply counterbalance each other and the sum of the pressures exerted by the atmosphere, indicated at 93, and

by the reduced air pressure, indicated at 90, apply a total pressure to the right as illustrated in FIG. 3, sufficient to'maintain the closure plate 28B in the closed and sealed position illustrated in FIG. 3. Hence, it will be understood that, as used in the claims, the phrase locking means for producing a sufficiently greater total pressure on said locking plate than the total pressure on said closure plate or similar phrases are broadly directed to either the FIG. 1 or FIG. 3 concept or their equivalents.

While there has been shown and described the preferred form of mechanism of this invention it will be apparent that various modifications and changes may be made therein, particularly in the form and relation of parts, without departing from the spirit of this invention as set forth in the appended claims.

We claim:

1. Improved apparatus for combination with a vessel defining a pressure chamber having an opening, said improvement comprising:

(a) a door member supported outside of said chamber for closing and sealing said opening;

(b) door locking means inside said chamber including a locking plate inside said chamber which is com nected to said door, said locking plate being constructed so as to be responsive to a greater total internal chamber pressure than the total internal chamber pressure on said closure plate in an opposite direction for maintaining said door in a closed position.

2. Improved apparatus for combination with a vessel defining a pressure chamber having an opening, said improvement comprising:

(a) a closure plate supported outside said chamber for closing and sealing said opening;

(b) closure plate locking means, including a locking plate inside said chamber which is connected to said closure plate for producing a sufliciently greater total pressure on said locking plate in a direction toward closure of said closure plate than the total pressure on said closure plate in an opposite direction thereby to maintain said closure plate in a closed position.

3. Improved apparatus for combination with a vessel defining a pressure chamber having an opening, said improvement comprising:

(a) a closure plate supported outside said chamber adapted for closing and sealing said opening when in a closed position, said plate having a first pressure responsive surface;

([1) closure plate locking means, including a locking plate inside said chamber connected to said closure plate in spaced relationship and having first and second pressure responsive surfaces and means in said chamber for substantially sealing said second surface of said locking plate from the internal pressure of said chamber, for producing a sufiiciently greater total pressure on said locking plate in a direction toward closure of said closure plate than the total pressure on said closure plate in the opposite direction thereby to maintain said closure plate in said closed position.

4. Apparatus in accordance with claim 3 in which: said first surface of said locking plate is larger than said first surface of said closure plate.

5. Apparatus in accordance with claim 3 in which said last mentioned means comprises: pressure reducnig means communicating with said second surface of said locking plate.

6. Apparatus in accordance with claim 3 including: pressure control means for selectively increasing and decreasing the pressure on said second surface sufi'icient to move said plates and connecting means respectively between said opened and closed positions.

7. Improved apparatus for combination with a vessel defining a pressure chamber having an opening, said improvement comprising:

(a) a closure plate adapted to close and seal said opening from outside said chamber when in a closed position, said plate having a first surface responsive to pressure within said chamber;

(b) closure plate locking means, including a locking plate connected in spaced relationship to said closure plate and having a first surface responsive to in ternal pressure of said chamber, for producing a sulficiently greater total pressure on said first surface of said locking member than on said first surface of said closure member when in substantially said closed position to lock said closure plate in substantially said closed position.

8. Improved apparatus for combination with a pressure chamber vessel having an internal longitudinally extending portion of uniform cross-section and an opening substantially in registry with said portion, said improvement comprising:

(a) a closure plate supported outside of said chamber adapted to close and seal said opening when in a closed position;

(b) closure plate locking means, including a locking plate connected in spaced relationship to said closure plate and being slidably sealed to the inside periphery of said uniform cross-section portion and pressure inlet means communicating with said chamber intermediate said plates when said closure plate is in said closed position, for producing a sufficiently greater total pressure on said locking plate in a direction toward closure of said closure plate than the total pressure on said closure plate in the opposite direction thereby to maintain said closure plate in said closed position.

9. Apparatus in accordance with claim 8 in which said last mentioned means includes: fluid pressure reducing means communicating with that end of said uniform crosssection portion opposite said opening.

10. Apparatus in accordance with claim 8 including:

(0) a second vessel defining a second pressure chamber of larger volumetric area than said first chamber and embracing said first vessel, said chambers being in open communication with each other.

11. Apparatus in accordance with claim 8 in which:

(0) said plates are connected by means defining a tray for supporting goods to be sterilized.

12. Improved apparatus for combination with a pressure chamber having an internal longitudinally extending portion of uniform cross-section, and an opening smaller than and in registry with the inside periphery of said portion, said improvement comprising:

(a) a closure plate supported outside of said chamber adapted to close and seal said opening when in a closed position;

(b) a larger locking plate connected to said closure plate in spaced relationship and substantially mating with the inside periphery of said uniform cross-section portion and slidably sealed therein;

(0) pressure inlet means communicating with said chamber intermediate said plates when said closure plate is in said closed position, and

(d) outlet means between that end of said portion opposite said opening and atmosphere to maintain substantially atmospheric pressure on an external surface of said locking plate.

13. Apparatus in accordance with claim 12 including:

(e) pressure control means connected to said outlet means for selectively increasing and decreasing pressure on an external surface of said locking plate facing away from said opening with sufiicient pressure to move said plates respectively between an open position and said closed position.

14. Sterilizer apparatus comprising, in combination,

(a) a vessel defining a steam chamber having front end and back ends,

(b) said vessel having a longitudinally extending portion of uniform cross-section terminating at said back end,

(0) said vessel having an opening in said front end smaller than and in registry with the inside periphery of said portion,

(d) a closure plate supported outside of said chamber adapted to close and seal said opening when in a closed position,

(e) a locking plate substantially mating with the inside periphery of said uniform cross-section portion and slidably sealed therein,

(f) conduit means extending from a source of steam pressure to a portion of said chamber intermediate said plates when said closure plate is in said closed position,

g) means extending through said opening for connecting said plates in spaced relationship, and

(h) a second opening extending through said back end of said vessel for maintaining substantially atmos- 5 pheric pressure intermediate said locking plate and said back end of the vessel. 15. Apparatus in accordance with claim 14 including: (i) pressure control means communicating with said second opening for selectively increasing and decreasing pressure intermediate said locking plate and said back end of the vessel sutficiently to move said plates and connecting means selectively between an open position and said closed position.

References Cited in the file of this patent UNITED STATES PATENTS 505,967 Sprague Oct. 3, 1893 1,015,847 Shields Jan. 30, 1912 1,359,875 Da Costa Nov. 23, 1920 1,755,895 Pupilla Apr. 22, 1930 2,505,302 Ramsey et al. Apr. 25, 1950 2,527,084 Smith Oct. 24, 1950 2,851,155 Ellingsen et a1 Sept. 9, 1958 FOREIGN PATENTS 879,447 Great Britain Oct. 11, 1961 

1. IMPROVED APPARATUS FOR COMBINATION WITH A VESSEL DEFINING A PRESSURE CHAMBER HAVING AN OPENING, SAID IMPROVEMENT COMPRISING: (A) A DOOR MEMBER SUPPORTED OUTSIDE OF SAID CHAMBER FOR CLOSING AND SEALING SAID OPENING; (B) DOOR LOCKING MEANS INSIDE SAID CHAMBER INCLUDING A LOCKING PLATE INSIDE SAID CHAMBER WHICH IS CONNECTED TO SAID DOOR, SAID LOCKING PLATE BEING CONSTRUCTED SO AS TO BE RESPONSIVE TO A GREATER TOTAL INTERNAL CHAMBER PRESSURE THAN THE TOTAL INTERNAL CHAMBER PRESSURE ON SAID CLOSURE PLATE IN AN OPPOSITE DIRECTION FOR MAINTAINING SAID DOOR IN A CLOSED POSITION. 